Metal fixation inserts are known, particularly in the ignition coils of automobile engines. These ignition coils include a casing of plastic material, in which tubular metal inserts are embedded during the molding, these inserts being pierced with bolts when the coil is installed. At one of their two axial ends, these tubular inserts form a bearing surface for the head of the bolt, and at their other axial end they form a bearing surface for the coil on its support.
These inserts of the known type are made by being cut from bar material, which is relatively tedious and has a certain number of other disadvantages.
First, these inserts are used in pairs, one insert of a pair generally having a "polarization" flange at one of its axial ends. The function of its flange, which when the coil is installed engages a countersunk face, is to assure that the coil is installed in the proper direction. The other insert of the coil does not have this flange and accordingly presses against a plane surface. As a result, two different types of inserts must be used.
In addition, when the casing of the coil is molded, the insert having the flange must be disposed in the proper location and in the right direction, with the threat of deterioration of the mold if these inserts are placed incorrectly.